1. Field of the Invention
The present invention relates to a thread cutting device in a sewing machine and particularly to a thread cutting machine which is operable to selectively cut both an upper thread and a lower thread and to cut only an upper thread.
2. Description of the Prior Art
A conventional thread cutting device in a sewing machine is disclosed in Japanese Laid-Open Utility Model Publication No. 2-67980 and includes a movable knife which is operable to cut both upper and lower threads through a reciprocal swinging movement across a space between a throat plate and a shuttle positioned below the throat plate. A lower thread retreating lever is swingably movable from a waiting position to an operative position, so that the lower thread is retreated from a thread cutting orbit of the movable knife. Thus, when the lower thread retreating lever is held at the waiting position, both the upper and lower threads are cut through movement of the movable knife. On the other hand, when the lower thread retreating lever has been moved from the waiting position to the operative position, only the upper thread is cut by the movable knife.
However, with this conventional thread cutting device, an actuator (a rotary solenoid) and its associated interlocking mechanism (a link mechanism) are disposed forwardly of the shuttle. Therefore, parts of these mechanisms may prevent an operation for changing a lower thread bobbin to another one or an operation for oiling the shuttle. Additionally, it is difficult to secure a space for mounting a lower thread detecting device.
Further, with the conventional thread cutting device, a setting operation of selection between two thread cutting modes, one for cutting both the upper and lower threads and the other for cutting only the upper thread is performed in connection with each cutting point during a sewing operation (an embroidery operation). Otherwise, in preparing sewing data (embroidery data), data with respect to selection between two thread cutting modes are set to be included in the sewing data. In these cases, a seriously troublesome amount of work is required for the setting operation if a number of thread cutting points are included in a pattern to be embroidered such as an embroidery pattern including a number of pattern parts.